dark lines coming from bright stars

[Somnium]

Hi all

i was wondering if anyone else has had the issue that i am having. after i stack my subs, i notice a black line going from bright stars to the edge of the detector. the strange thing is i cant see it in the subs, only in the stacked version (DSS)

PS. forget the blobby stars, i had some differential flexure problems

[Atmos]

Imaging past the meridian? My thought is a very minute amount of mirror movement when going from one side of the sky to the other. If the diffraction spike is very slightly moved from one side of a star to the other on different sides of the meridian.

[RobF]

That's an issue with the QHY9 with some drivers and settings Aidan. Clamping is the first thing usually suggested to help. I've found different drivers and download speeds affect the likelihood of seeing it too over the years.

Have you got the clamping tick box selected?

[RickS]

The KAF-8300 can produce short, dark horizontal blooms from bright stars when binned because the horizontal shift register isn't deep enough. That doesn't look exactly the same but I wonder if it might be a similar effect. Are you binning? Have you changed the gain? The fix for the blooming problem when binned is to reduce the gain.

Cheers,
Rick.

[Somnium]

I am not binning , I have never heard of clamping, I will check that out, I am using ezcap to take images. I can't really see evidence of the lines in each sub but that might just be because I haven't stretched it as much. I am out for about 2 hours, will check my settings when I get home . Thanks

[Somnium]

there is no option for clamping in EZcap ...

any suggestion on the best driver to use for the QHY9 ?

[Somnium]

just an addition to an earlier comment, the lines do appear in the subs, they are just extremely faint and it required some stretching to find them

[Shiraz]

any use?
http://www.iceinspace.com.au/forum/showthread.php?t=130615
I think this is an issue with the ABG bias setting.

[Somnium]

Thanks Ray, that looks identical to the issue i am getting, i haven't had a chance to fully digest the thread, but it seems like i am going to have to open the camera up and do some surgery on it ... i would have thought if it is an issue it should be resolved by the manufacturer.

[Shiraz]

I doubt that anything more than a tweak on the pot will be needed. I think that Allan set the bias on his to 2.2v and the problem went away. Maybe check with Theo and see if he has any info from the factory?

Allan did everyone a service by publishing the info in that thread :thumbsup:

[Somnium]

Hi Rob, I found clamping on ezcap and it was unchecked.

[RobF]

Nothing to lose by giving it a try before you "operate" :)

[Somnium]

yeah, the manual says that if it is checked than it can cause this issue. i am going to play around with my gain and offset first too, because they are not right, if i am still having the issues i will scrub up.